排查linux CentOS7.6的mysql(5.7.27)内存泄漏因OOM被系统kill的问题

mysql版本：5.7.27
mysql业务：因业务需要，每天需生成大量的表

一，查询系统日志得知mysql因OOM被kill了

1.查询硬盘上永久保存的系统日志

journalctl命令： journalctl -k | grep -i "oom|kill|error"
可加时间参数： journalctl -k --since "2026-04-09 00:00" --until "2026-04-10 10:00" | grep -i "oom|kill|error"

查询结果：

bash 复制代码

[root@db ~]# journalctl -k  | grep -i "oom\|kill\|error"
12月 21 11:45:38 localhost.localdomain kernel: HEST: Enabling Firmware First mode for corrected errors.
12月 21 11:45:38 localhost.localdomain kernel: ERST: Error Record Serialization Table (ERST) support is initialized.
4月 09 22:43:08 27 kernel: mysqld invoked oom-killer: gfp_mask=0x201da, order=0, oom_score_adj=0
4月 09 22:43:08 27 kernel:  [<ffffffffb7fba274>] oom_kill_process+0x254/0x3d0
4月 09 22:43:08 27 kernel: [ pid ]   uid  tgid total_vm      rss nr_ptes swapents oom_score_adj name
4月 09 22:43:08 27 kernel: [22186]     0 22186   130450        0      40      192             0 gsd-rfkill
4月 09 22:43:08 27 kernel: Out of memory: Kill process 358400 (mysqld) score 565 or sacrifice child
4月 09 22:43:08 27 kernel: Killed process 358400 (mysqld) total-vm:80464500kB, anon-rss:76302072kB, file-rss:0kB, shmem-rss:0kB
[root@db ~]#

二，查看内存情况

共125G，只剩余19G了，已经用了 104G，内存压力非常大。Swap 已经满了（4G 全用光），说明系统之前内存严重不够用，开始频繁用交换分区，机器大概率会很卡。

bash 复制代码

[root@db ~]# free -h
              total        used        free      shared  buff/cache   available
Mem:           125G        104G        632M         42M         20G         19G
Swap:          4.0G        4.0G          0B
[root@db ~]# 



[root@db ~]# free -mt
              total        used        free      shared  buff/cache   available
Mem:         128419      107275         630          42       20513       19963
Swap:          4095        4095           0
Total:       132515      111371         630
[root@db ~]#

排查104G都是谁在用：ps aux --sort=-%mem | head -20

可以看到有两个mysql的实例占比很大

bash 复制代码

[root@db ~]# ps aux --sort=-%mem | head -20
USER        PID %CPU %MEM    VSZ   RSS TTY      STAT START   TIME COMMAND
mysql    358200  6.3 44.2 62294972 58240152 ?   Ssl   2024 75570:49 /home/mysql/mysql4001/bin/mysqld --defaults-file=/home/mysql/mysql4001/etc/my4001.cnf
mysql    438278 39.7 34.4 47782108 45246208 ?   Ssl  4月10 3930:05 /home/mysql/mysql4002/bin/mysqld --defaults-file=/home/mysql/mysql4002/etc/my4002.cnf
mysql    358916  0.5  1.1 3068732 1558772 ?     Ssl   2024 5973:52 /home/mysql/mysql4005/bin/mysqld --defaults-file=/home/mysql/mysql4005/etc/my4005.cnf
mysql    358563 18.6  0.5 2928924 733824 ?      Ssl   2024 220969:14 /home/mysql/mysql4003/bin/mysqld --defaults-file=/home/mysql/mysql4003/etc/my4003.cnf
mysql    358753  0.0  0.4 2928924 558060 ?      Ssl   2024 1003:10 /home/mysql/mysql4004/bin/mysqld --defaults-file=/home/mysql/mysql4004/etc/my4004.cnf
root      22229  2.9  0.1 896844 221296 ?       Sl    2023 35667:54 /usr/libexec/gsd-color
root      22314  0.0  0.1 1551592 197708 ?      Sl    2023  35:15 /usr/bin/gnome-software --gapplication-service
root      21991  0.0  0.1 7978324 138220 ?      Sl    2023 245:57 /usr/bin/gnome-shell
root      22223  0.0  0.0 1257612 50020 ?       S<l   2023   2:43 /usr/bin/pulseaudio --start
root       9665  0.0  0.0  80760 39028 ?        Ss    2023   6:05 /usr/lib/systemd/systemd-journald
root      23957  0.0  0.0 742040 27724 ?        Ssl   2023  56:16 /usr/sbin/rsyslogd -n
zabbix   438476  1.1  0.0 3222388 20768 ?       Ssl  4月10 109:28 /usr/sbin/zabbix_agent2 -c /etc/zabbix/zabbix_agent2.conf
root      19201  0.0  0.0 489016 15316 tty1     Ssl+  2023   5:17 /usr/bin/X :0 -background none -noreset -audit 4 -verbose -auth /run/gdm/auth-for-gdm-RFUQyH/database -seat seat0 vt1
root     114164  0.0  0.0 160844  5792 ?        Ss   13:55   0:00 sshd: root@pts/0
root      18169  0.0  0.0 120132  5500 ?        S     2023 419:12 /bin/bash /usr/sbin/ksmtuned
root      22354  0.0  0.0 591484  5364 ?        Sl    2023   0:03 /usr/libexec/tracker-store
root          1  0.0  0.0 197652  4624 ?        Ss    2023  31:25 /usr/lib/systemd/systemd --switched-root --system --deserialize 22
root      19497  0.0  0.0 487764  4528 ?        Ssl   2023  11:27 /usr/libexec/packagekitd
root      22236  0.0  0.0 1143196 3396 ?        Sl    2023   2:26 /usr/libexec/gsd-media-keys

3.排查mysql实例内存大的原因

查看InnoDB 缓冲池大小：show variables like 'innodb_buffer_pool_size';
查看InnoDB 缓冲池切成几个小池：show variables like 'innodb_buffer_pool_instances';
查看当前内存实际使用：sql查询tables信息
查看缓冲池使用率（判断是否真的需要这么大）：SHOW ENGINE INNODB STATUS;

bash 复制代码

MySQL [(none)]> show variables like 'innodb_buffer_pool_size';
+-------------------------+------------+
| Variable_name           | Value      |
+-------------------------+------------+
| innodb_buffer_pool_size | 4294967296 |
+-------------------------+------------+
1 row in set (0.18 sec)

MySQL [(none)]> show variables like 'innodb_buffer_pool_instances';
+------------------------------+-------+
| Variable_name                | Value |
+------------------------------+-------+
| innodb_buffer_pool_instances | 8     |
+------------------------------+-------+
1 row in set (0.00 sec)



MySQL [(none)]> SELECT
    ->   engine,
    ->   COUNT(*) AS tables,
    ->   SUM(data_length) / 1024 / 1024 / 1024 AS data_size_gb,
    ->   SUM(index_length) / 1024 / 1024 / 1024 AS index_size_gb,
    ->   (SUM(data_length) + SUM(index_length)) / 1024 / 1024 / 1024 AS total_size_gb
    -> FROM information_schema.tables
    -> WHERE table_schema NOT IN ('mysql','sys','information_schema','performance_schema')
    -> GROUP BY engine;
+--------+--------+-------------------+------------------+-------------------+
| engine | tables | data_size_gb      | index_size_gb    | total_size_gb     |
+--------+--------+-------------------+------------------+-------------------+
| InnoDB | 211469 | 7853.475524902344 | 184.029800415039 | 8037.505325317383 |
+--------+--------+-------------------+------------------+-------------------+
1 row in set (30 min 20.96 sec)





MySQL [(none)]> SHOW ENGINE INNODB STATUS;
+--------+------+---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| Type   | Name | Status                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                           |
+--------+------+---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| InnoDB |      | 
=====================================
2026-04-17 11:57:57 0x7f766c21f700 INNODB MONITOR OUTPUT
=====================================
Per second averages calculated from the last 27 seconds
-----------------
BACKGROUND THREAD
-----------------
srv_master_thread loops: 567449 srv_active, 0 srv_shutdown, 1124 srv_idle
srv_master_thread log flush and writes: 568573
----------
SEMAPHORES
----------
OS WAIT ARRAY INFO: reservation count 83450578
OS WAIT ARRAY INFO: signal count 51958414
RW-shared spins 0, rounds 1175431, OS waits 271863
RW-excl spins 0, rounds 33204095, OS waits 900821
RW-sx spins 48467, rounds 1400486, OS waits 44214
Spin rounds per wait: 1175431.00 RW-shared, 33204095.00 RW-excl, 28.90 RW-sx
------------
TRANSACTIONS
------------
Trx id counter 8298046688
Purge done for trx's n:o < 8298039869 undo n:o < 0 state: running but idle
History list length 48
LIST OF TRANSACTIONS FOR EACH SESSION:
---TRANSACTION 421626915763152, not started
0 lock struct(s), heap size 1136, 0 row lock(s)
---TRANSACTION 421626915755856, not started
0 lock struct(s), heap size 1136, 0 row lock(s)
---TRANSACTION 421626915762240, not started
0 lock struct(s), heap size 1136, 0 row lock(s)
---TRANSACTION 421626915761328, not started
0 lock struct(s), heap size 1136, 0 row lock(s)
---TRANSACTION 421626915760416, not started
0 lock struct(s), heap size 1136, 0 row lock(s)
---TRANSACTION 421626915758592, not started
0 lock struct(s), heap size 1136, 0 row lock(s)
---TRANSACTION 421626915757680, not started
0 lock struct(s), heap size 1136, 0 row lock(s)
---TRANSACTION 421626915759504, not started
0 lock struct(s), heap size 1136, 0 row lock(s)
---TRANSACTION 421626915756768, not started
0 lock struct(s), heap size 1136, 0 row lock(s)
--------
FILE I/O
--------
I/O thread 0 state: waiting for completed aio requests (insert buffer thread)
I/O thread 1 state: waiting for completed aio requests (log thread)
I/O thread 2 state: waiting for completed aio requests (read thread)
I/O thread 3 state: waiting for completed aio requests (read thread)
I/O thread 4 state: waiting for completed aio requests (read thread)
I/O thread 5 state: waiting for completed aio requests (read thread)
I/O thread 6 state: complete io for buf page (write thread)
I/O thread 7 state: waiting for completed aio requests (write thread)
I/O thread 8 state: waiting for completed aio requests (write thread)
I/O thread 9 state: waiting for completed aio requests (write thread)
Pending normal aio reads: [0, 0, 0, 0] , aio writes: [0, 0, 0, 0] ,
 ibuf aio reads:, log i/o's:, sync i/o's:
Pending flushes (fsync) log: 0; buffer pool: 1
1839346 OS file reads, 45639629 OS file writes, 25692445 OS fsyncs
0.04 reads/s, 16384 avg bytes/read, 73.70 writes/s, 44.48 fsyncs/s
-------------------------------------
INSERT BUFFER AND ADAPTIVE HASH INDEX
-------------------------------------
Ibuf: size 1, free list len 0, seg size 2, 0 merges
merged operations:
 insert 0, delete mark 0, delete 0
discarded operations:
 insert 0, delete mark 0, delete 0
Hash table size 1182691, node heap has 1 buffer(s)
Hash table size 1182691, node heap has 1 buffer(s)
Hash table size 1182691, node heap has 1 buffer(s)
Hash table size 1182691, node heap has 3 buffer(s)
Hash table size 1182691, node heap has 6 buffer(s)
Hash table size 1182691, node heap has 1 buffer(s)
Hash table size 1182691, node heap has 2 buffer(s)
Hash table size 1182691, node heap has 1 buffer(s)
309.43 hash searches/s, 94.89 non-hash searches/s
---
LOG
---
Log sequence number 10160844592918
Log flushed up to   10160844554224
Pages flushed up to 10160835836712
Last checkpoint at  10160833904291
0 pending log flushes, 0 pending chkp writes
2090588 log i/o's done, 3.89 log i/o's/second
----------------------
BUFFER POOL AND MEMORY
----------------------
Total large memory allocated 4397727744
Dictionary memory allocated 17237151
Buffer pool size   262112
Free buffers       8191
Database pages     253905
Old database pages 93563
Modified db pages  1282
Pending reads      0
Pending writes: LRU 0, flush list 2, single page 0
Pages made young 2437456, not young 12694603
0.00 youngs/s, 0.00 non-youngs/s
Pages read 1423368, created 12127375, written 36978151
0.00 reads/s, 0.00 creates/s, 0.00 writes/s
Buffer pool hit rate 1000 / 1000, young-making rate 0 / 1000 not 0 / 1000
Pages read ahead 0.00/s, evicted without access 0.00/s, Random read ahead 0.00/s
LRU len: 253905, unzip_LRU len: 0
I/O sum[24328]:cur[395], unzip sum[0]:cur[0]
----------------------
INDIVIDUAL BUFFER POOL INFO
----------------------
---BUFFER POOL 0
Buffer pool size   32764
Free buffers       1024
Database pages     31738
Old database pages 11695
Modified db pages  140
Pending reads      0
Pending writes: LRU 0, flush list 0, single page 0
Pages made young 303218, not young 1522120
0.00 youngs/s, 0.00 non-youngs/s
Pages read 177929, created 1518448, written 4992441
0.00 reads/s, 0.00 creates/s, 0.00 writes/s
Buffer pool hit rate 1000 / 1000, young-making rate 0 / 1000 not 0 / 1000
Pages read ahead 0.00/s, evicted without access 0.00/s, Random read ahead 0.00/s
LRU len: 31738, unzip_LRU len: 0
I/O sum[3041]:cur[49], unzip sum[0]:cur[0]
---BUFFER POOL 1
Buffer pool size   32764
Free buffers       1023
Database pages     31736
Old database pages 11695
Modified db pages  198
Pending reads      0
Pending writes: LRU 0, flush list 0, single page 0
Pages made young 330495, not young 1711760
0.00 youngs/s, 0.00 non-youngs/s
Pages read 178787, created 1524171, written 4563514
0.00 reads/s, 0.00 creates/s, 0.00 writes/s
Buffer pool hit rate 1000 / 1000, young-making rate 0 / 1000 not 0 / 1000
Pages read ahead 0.00/s, evicted without access 0.00/s, Random read ahead 0.00/s
LRU len: 31736, unzip_LRU len: 0
I/O sum[3041]:cur[49], unzip sum[0]:cur[0]
---BUFFER POOL 2
Buffer pool size   32764
Free buffers       1024
Database pages     31737
Old database pages 11695
Modified db pages  165
Pending reads      0
Pending writes: LRU 0, flush list 2, single page 0
Pages made young 324339, not young 1683372
0.00 youngs/s, 0.00 non-youngs/s
Pages read 178189, created 1518713, written 4287636
0.00 reads/s, 0.00 creates/s, 0.00 writes/s
Buffer pool hit rate 1000 / 1000, young-making rate 0 / 1000 not 0 / 1000
Pages read ahead 0.00/s, evicted without access 0.00/s, Random read ahead 0.00/s
LRU len: 31737, unzip_LRU len: 0
I/O sum[3041]:cur[49], unzip sum[0]:cur[0]
---BUFFER POOL 3
Buffer pool size   32764
Free buffers       1024
Database pages     31739
Old database pages 11696
Modified db pages  195
Pending reads      0
Pending writes: LRU 0, flush list 0, single page 0
Pages made young 296753, not young 1508495
0.00 youngs/s, 0.00 non-youngs/s
Pages read 176588, created 1516645, written 4523849
0.00 reads/s, 0.00 creates/s, 0.00 writes/s
Buffer pool hit rate 1000 / 1000, young-making rate 0 / 1000 not 0 / 1000
Pages read ahead 0.00/s, evicted without access 0.00/s, Random read ahead 0.00/s
LRU len: 31739, unzip_LRU len: 0
I/O sum[3041]:cur[49], unzip sum[0]:cur[0]
---BUFFER POOL 4
Buffer pool size   32764
Free buffers       1024
Database pages     31739
Old database pages 11696
Modified db pages  157
Pending reads      0
Pending writes: LRU 0, flush list 0, single page 0
Pages made young 282041, not young 1639408
0.00 youngs/s, 0.00 non-youngs/s
Pages read 176711, created 1508214, written 4766030
0.00 reads/s, 0.00 creates/s, 0.00 writes/s
Buffer pool hit rate 1000 / 1000, young-making rate 0 / 1000 not 0 / 1000
Pages read ahead 0.00/s, evicted without access 0.00/s, Random read ahead 0.00/s
LRU len: 31739, unzip_LRU len: 0
I/O sum[3041]:cur[49], unzip sum[0]:cur[0]
---BUFFER POOL 5
Buffer pool size   32764
Free buffers       1024
Database pages     31738
Old database pages 11695
Modified db pages  190
Pending reads      0
Pending writes: LRU 0, flush list 0, single page 0
Pages made young 283485, not young 1605397
0.00 youngs/s, 0.00 non-youngs/s
Pages read 178423, created 1513823, written 4887543
0.00 reads/s, 0.00 creates/s, 0.00 writes/s
Buffer pool hit rate 1000 / 1000, young-making rate 0 / 1000 not 0 / 1000
Pages read ahead 0.00/s, evicted without access 0.00/s, Random read ahead 0.00/s
LRU len: 31738, unzip_LRU len: 0
I/O sum[3041]:cur[50], unzip sum[0]:cur[0]
---BUFFER POOL 6
Buffer pool size   32764
Free buffers       1024
Database pages     31740
Old database pages 11696
Modified db pages  115
Pending reads      0
Pending writes: LRU 0, flush list 0, single page 0
Pages made young 273763, not young 1592887
0.00 youngs/s, 0.00 non-youngs/s
Pages read 178941, created 1510240, written 4480946
0.00 reads/s, 0.00 creates/s, 0.00 writes/s
Buffer pool hit rate 1000 / 1000, young-making rate 0 / 1000 not 0 / 1000
Pages read ahead 0.00/s, evicted without access 0.00/s, Random read ahead 0.00/s
LRU len: 31740, unzip_LRU len: 0
I/O sum[3041]:cur[50], unzip sum[0]:cur[0]
---BUFFER POOL 7
Buffer pool size   32764
Free buffers       1024
Database pages     31738
Old database pages 11695
Modified db pages  122
Pending reads      0
Pending writes: LRU 0, flush list 0, single page 0
Pages made young 343362, not young 1431164
0.00 youngs/s, 0.00 non-youngs/s
Pages read 177800, created 1517121, written 4476192
0.00 reads/s, 0.00 creates/s, 0.00 writes/s
Buffer pool hit rate 1000 / 1000, young-making rate 0 / 1000 not 0 / 1000
Pages read ahead 0.00/s, evicted without access 0.00/s, Random read ahead 0.00/s
LRU len: 31738, unzip_LRU len: 0
I/O sum[3041]:cur[50], unzip sum[0]:cur[0]
--------------
ROW OPERATIONS
--------------
0 queries inside InnoDB, 0 queries in queue
0 read views open inside InnoDB
Process ID=438278, Main thread ID=140146741806848, state: sleeping
Number of rows inserted 281036613, updated 0, deleted 0, read 170516033
184.22 inserts/s, 0.00 updates/s, 0.00 deletes/s, 0.00 reads/s
----------------------------
END OF INNODB MONITOR OUTPUT
============================
 |
+--------+------+---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
1 row in set (0.24 sec)

结果

innodb_buffer_pool_size = 4GB
物理内存占用：43.1G
业务：疯狂 INSERT 日志表，单库 21 万 + 张表
运行时长：几十天（因oom被kill后重启过）

验证Open_tables情况

bash 复制代码

#4001实例：

MySQL [(none)]> show global status like 'Open_tables';
+---------------+-------+
| Variable_name | Value |
+---------------+-------+
| Open_tables   | 1984  |
+---------------+-------+
1 row in set (0.00 sec)

MySQL [(none)]> show global status like 'Opened_tables';
+---------------+------------+
| Variable_name | Value      |
+---------------+------------+
| Opened_tables | 1154279575 |
+---------------+------------+
1 row in set (0.01 sec)


#4002实例：

MySQL [(none)]> show global status like 'Open_tables';
+---------------+-------+
| Variable_name | Value |
+---------------+-------+
| Open_tables   | 1984  |
+---------------+-------+
1 row in set (0.03 sec)

MySQL [(none)]> show global status like 'Opened_tables';
+---------------+-----------+
| Variable_name | Value     |
+---------------+-----------+
| Opened_tables | 188864678 |
+---------------+-----------+
1 row in set (0.01 sec)

5.进入mysql的performance_schema库查询相关信息

5.1 查询MySQL里谁消耗的内存：
select event_name,SUM_NUMBER_OF_BYTES_ALLOC
from memory_summary_global_by_event_name
order by SUM_NUMBER_OF_BYTES_ALLOC desc LIMIT 10;

bash 复制代码

MySQL [performance_schema]> select event_name,SUM_NUMBER_OF_BYTES_ALLOC 
    -> from memory_summary_global_by_event_name
    -> order by SUM_NUMBER_OF_BYTES_ALLOC desc LIMIT 10;
+----------------------------------------------------------------------+---------------------------+
| event_name                                                           | SUM_NUMBER_OF_BYTES_ALLOC |
+----------------------------------------------------------------------+---------------------------+
| memory/performance_schema/file_instances                             |                 299892736 |
| memory/performance_schema/table_shares                               |                 218103808 |
| memory/performance_schema/table_handles                              |                 171048960 |
| memory/performance_schema/table_io_waits_summary_by_index_usage      |                 149946368 |
| memory/performance_schema/rwlock_instances                           |                  83230720 |
| memory/performance_schema/mutex_instances                            |                  20316160 |
| memory/performance_schema/events_statements_history_long             |                  14320000 |
| memory/performance_schema/events_statements_history_long.tokens      |                  10240000 |
| memory/performance_schema/events_statements_summary_by_digest.tokens |                  10240000 |
| memory/performance_schema/events_statements_history_long.sqltext     |                  10240000 |
+----------------------------------------------------------------------+---------------------------+
10 rows in set (0.20 sec)

5.2 哪些内部线程消耗了内存
select event_name, SUM_NUMBER_OF_BYTES_ALLOC
from memory_summary_by_thread_by_event_name
order by SUM_NUMBER_OF_BYTES_ALLOC desc limit 20;

bash 复制代码

MySQL [performance_schema]> select event_name, SUM_NUMBER_OF_BYTES_ALLOC 
    -> from memory_summary_by_thread_by_event_name
    -> order by SUM_NUMBER_OF_BYTES_ALLOC desc limit 20;
+----------------------------------------------+---------------------------+
| event_name                                   | SUM_NUMBER_OF_BYTES_ALLOC |
+----------------------------------------------+---------------------------+
| memory/archive/record_buffer                 |                         0 |
| memory/sql/QUICK_RANGE_SELECT::alloc         |                         0 |
| memory/sql/table_mapping::m_mem_root         |                         0 |
| memory/sql/sp_head::call_mem_root            |                         0 |
| memory/sql/sp_head::execute_mem_root         |                         0 |
| memory/sql/sp_head::main_mem_root            |                         0 |
| memory/sql/THD::sp_cache                     |                         0 |
| memory/sql/Warning_info::m_warn_root         |                         0 |
| memory/sql/Protocol_local::m_rset_root       |                         0 |
| memory/sql/Prepared_statement::main_mem_root |                         0 |
| memory/sql/Prepared_statement_map            |                         0 |
| memory/sql/servers                           |                         0 |
| memory/sql/Table_triggers_list               |                         0 |
| memory/sql/gdl                               |                         0 |
| memory/sql/new_frm_mem                       |                         0 |
| memory/sql/help                              |                         0 |
| memory/sql/thd::main_mem_root                |                         0 |
| memory/sql/Delegate::memroot                 |                         0 |
| memory/sql/THD::transactions::mem_root       |                         0 |
| memory/sql/display_table_locks               |                         0 |
+----------------------------------------------+---------------------------+
20 rows in set (0.05 sec)

table_shares：表结构缓存，218M
table_handles：表打开句柄，171M
file_instances：表文件句柄，299M
这三个加起来 ≈ 700M，但这只是 performance_schema 统计的，真实泄漏的是：底层 C++ 层内存，不进 performance_schema！

三，结论：MySQL 5.7 在高频打开新表场景下的内存泄漏，导致内存只增不减，最终占满 100G

结论
两个 MySQL 内存暴涨 98G 的真正原因：
MySQL 5.7 高并发 + 高频创建新表 + 表结构频繁刷新 → 内存泄漏（table cache 层）
不是表多、不是 buffer pool、不是配置，就是官方 BUG 导致的内存泄漏！

原因：

看Open_tables情况

bash 复制代码

#4001

Open_tables:      1984      → 当前打开的表（正常，很小）
Opened_tables: 11亿+       → 历史累计打开过的表（天文数字！）

#4002

Open_tables:      1984      → 当前打开的表（正常）
Opened_tables: 1.8亿+      → 历史累计打开过的表（巨大！）

2.1 Open_tables = 1984
- MySQL 当前只打开了 1984 张表
- 表缓存没有爆
- 不是表太多占内存
2.2 Opened_tables = 11 亿 / 1.8 亿
- 业务不断创建新表（每天按设备建表）
- 不断打开 → 关闭 → 打开 → 关闭
- MySQL 5.7 在高频打开关闭表时，存在无法回收的内存泄漏
2.3 泄漏的是什么内存？
- 表定义（frm）、字典缓存、临时对象、metadata 锁资源
- 这些内存只分配不释放
- 运行越久 → 泄漏越多 → 内存涨到几十 G

InnoDB 本身只用了一点点内存，其余全是上层泄漏。Opened_tables 高达 1.8亿 ~ 11亿，只有高频创表、高频删表、高频开表才会出现这种值。业务模式：每天为每个设备创建一张新表 → 极高频率打开新表 → 触发 MySQL 5.7 内存泄漏。这是 MySQL 5.7 官方公开的经典泄漏场景。

四，方案

调整业务，清理不用的表
升级 MySQL 版本：5.7.39 及以上
调整 my.cnf（降低泄漏速度）

bash 复制代码

table_open_cache = 1024
table_definition_cache = 1024
max_connections = 500

排查linux CentOS7.6的mysql(5.7.27)内存泄漏因OOM被系统kill的问题

一，查询系统日志得知mysql因OOM被kill了

二，查看内存情况

三， 结论：MySQL 5.7 在高频打开新表场景下的内存泄漏，导致内存只增不减，最终占满 100G

四，方案

三，结论：MySQL 5.7 在高频打开新表场景下的内存泄漏，导致内存只增不减，最终占满 100G